Doc Manley Novelties Optimale Men's Sexual Overall health line. Optimale C-Ring Thick 40mm Black. For Added Thick results, take a look at the OptiMALE 40mm C-Ring! Made from soft, stretchable silicone for simple use round the shaft or testicles, these cock rings are perfectly suited to allowing the most optimal of erections, and prolonging ejaculation. Offered in three individual sizes: 35mm, 40mm, and 45mm collect all of them! Obtainable in Black and Slate. Phthalate-free. Updated March 7, 2014